President Obama renewed his plea for gun control Monday on the heels of a "60 Minutes" interview featuring the families of Newtown. NBC's Chuck Todd reports.

By Kasie Hunt, Political Reporter, NBC News

With the families of children killed in last year’s Newtown school shooting looking on, President Barack Obama on Monday made an emotional plea for Americans to urge Congress to pass new gun control measures.

"We all have to stand up," Obama said in a speech in Hartford, Conn., where he flew to try and maintain faltering momentum for a package of new gun laws the Senate could take up this week. "If you want the people you send to Washington to have just an iota of courage that the educators at Sandy Hook showed when danger arrived on their doorstep, then we'll all have to stand up."

As Obama was speaking -- and the crowd was chanting, "we want a vote" -- the Senate's top Republican announced he would join a GOP filibuster of gun control legislation and oppose allowing a Democratic gun control bill to come to the Senate floor for debate

Senate Minority Leader Mitch McConnell did leave the door open to allowing a gun control compromise bill to come to the floor, but his office said in a statement that he will oppose the version of the legislation that Reid outlined before the Senate's just-concluded two week recess.

Eleven parents and spouses of Newtown victims were set to board Air Force One to fly to Washington after the speech, where they'll spend three days lobbying Congress to pass the new gun safety laws.

The Senate is poised to start debating and voting on gun laws as early as this week.

But after weeks of negotiations, the gun bill is a much less ambitious proposal than what Obama and Vice President Joe Biden first pushed for in the days after Newtown, where 20 schoolchildren and 6 adults were killed.

Legislation proposed in the wake of the shooting included a renewal of a lapsed assault weapons ban and measures to limit high capacity magazines. Senate Majority Leader Harry Reid has pledged that the upper chamber will vote on those measures, but both are likely doomed to fail.

Now, lawmakers are fighting over expanding background checks to cover most gun sales. Under current law, Americans can buy firearms at a gun show or online without getting a background check.

"We have to tell Congress its time to require a background check for anyone who wants to buy a gun so people who are dangerous to themselves and others cannot get their hands on a gun," Obama said Monday.

Senators are still negotiating a compromise proposal on background checks, and Republican Sen. Pat Toomey of Pennsylvania is in talks with Democratic Sen. Joe Manchin of West Virginia to try and find a bipartisan agreement.

But with the upper chamber set to begin debating gun control soon, they're running out of time.